Starting out, I have a condition or two to follow in contributing to this universe.

First, all story ideas are run through by me first via PM.

Second, the main characters have this canon template to their background.

Twilight Sparkle:
Same as usual, just living in her old tower instead.

Minuette:
Is a member of the Timekeepers guild(I suspect there's a reason so many ponies cutie marks are hourglasses. They're basically a union in each town responsible for keeping the city facilities, bureaucracy, maintenance/development, and scheduling running like clockwork. Minuette's primary charge are dental appointments )

Lemon Hearts:
An event planner intern at the palace under Raven. Is a big stickler for manners and politeness.

Twinkleshine:
Has a family line of working in photography and even owns a small photoshop. Has a big passion for scrapbooking and always looks for a memento every time she goes or tries something new.

Lyra Heartstrings:
Commutes to Ponyville on weekends and holidays. Her specially hand magic is used for many things 'hand related'(knocking, hitchhiking, playing her lyre, victory pose). A musical arts major with a minor in cryptozoology(wants to study myths and mythical beings for a living, but falls back on her music for stable income).

Moondancer:
Is as smart and as studious as Twilight, but whereas Twilight's factoids are more commonplace, her's are a trivia juggernaut(ex: Twilight could tell you the name of a town, its founder, and current statistics and demography, while Moondancer would point out its longest road, its oldest restaurant, and a local incident that happened around the founder's statue at a certain year while listing the names involved.)

All still study at least part time at Celestia's school for gifted unicorns.